A cloud service has come to be known to public because nowadays an Internet is widely used. According to the cloud service, a user can be provided with a service utilizing programs, data or the like via the Internet instead of storing programs or data in a local storage at an office or home to utilize them.
As the cloud service is widely used, there is an increasing interest in security of data on the cloud. In this connection, according to a known technique, the data on the cloud is encrypted in order to preserve the security.
However, if the data on the cloud is encrypted, the user cannot directly check the content of the data or perform a search. According to an example of a way of searching for the encrypted data, metadata is attached to the encrypted data and the metadata is to be searched (see Patent Document 1). Since the metadata is not encrypted, the user can check the content of the data from the metadata and perform the search using the metadata.
Patent Document 1 discloses an image forming apparatus in which scanned image data is associated with an ID input by the user, and when there is a demand to read information stored in a storage part, the user who requests the process is made to input his/her ID, and if the input user ID corresponds to the user ID associated with the image data, an access to the demanded image data is permitted.
However, Patent Document 1 does not consider the utilization of the cloud service and does not disclose how to edit, etc., the metadata of the image data on the Internet. Further, even if the data is encrypted, the access to the metadata should be limited depending on an authority; however, Patent Document 1 does not consider the access limit to the metadata in the cloud service.
[Patent Document 2] Japanese Laid-open Patent Publication No. 2006-339928